Texas Instruments TRF7970A Manual page 58

TRF7970A
SLOS743L – AUGUST 2011 – REVISED MARCH 2017
6.15.3 Detailed Register Description
6.15.3.1 Main Configuration Registers
6.15.3.1.1 Chip Status Control Register (0x00)
Table 6-25 describes the Chip Status Control register.
Function: Control of Power mode, RF on or off, Active or Passive mode, Direct mode
Default: 0x01, preset at EN = L or POR = H
Bit Name
1 = Standby mode
B7 stby
0 = Active mode
1 = Direct mode 0 or 1
B6 direct
0 = Direct l 2 (default)
1 = RF output active
B5 rf_on
0 = RF output not active
1 = Half output power
B4 rf_pwr
0 = Full output power
1 = Selects aux RX input
B3 pm_on
0 = Selects main RX input
B2 Reserved
1 = Receiver activated for
external field measurement
B1 rec_on
0 = Automatic enable
1 = 5-V operation
B0 vrs5_3
0 = 3-V operation
6.15.3.1.2 ISO Control Register (0x01)
Table 6-26 describes the ISO Control register.
Function: Controls the selection of ISO standard protocol, direct mode and receive CRC
Default: 0x02 (ISO/IEC 15693 high bit rate, one subcarrier, 1 out of 4); it is preset at EN = L or POR = H
Bit Name
B7 rx_crc_n CRC Receive selection
B6 dir_mode Direct mode type selection
B5 rfid RFID / Reserved
B4 iso_4 RFID / NFC Target
(1) Only applicable to ISO/IEC 14443 A and ISO/IEC 15693
58 Detailed Description
Table 6-25. Chip Status Control Register (0x00)
Function
Standby mode keeps all supply regulators and the 13.56-MHz SYS_CLK
oscillator running. (Typical start-up time to full operation is 100 µs.)
Active mode (default)
Provides user direct access to AFE (direct mode 0) or allows user to add
custom framing (direct mode 1). Bit 6 of the ISO Control register must be set by
user before entering direct mode 0 or 1.
Uses SPI or parallel communication with automatic framing and ISO decoders
Transmitter on, receivers on
Transmitter off
TX_OUT (pin 5) = 8-Ω output impedance P = 100 mW (20 dBm) at 5 V,
P = 33 mW (+15 dBm) at 3.3 V
TX_OUT (pin 5) = 4-Ω output impedance P = 200 mW (+23 dBm) at 5 V,
P = 70 mW (+18 dBm) at 3.3 V
RX_IN2 input is used
RX_IN1 input is used
Forced enabling of receiver and TX oscillator. Used for external field
measurement.
Allows enable of the receiver by bit 5 of this register (0x00)
Selects the V
Table 6-26. ISO Control Register (0x01)
Function
0 = RX CRC (CRC is present in the response)
1 = no RX CRC (CRC is not present in the response)
0 = Direct Mode 0
1 = Direct mode 1
0 = RFID mode
1 = NFC or card emulation mode
RFID: See
NFC:
0 = target
1 = initiator
Submit Documentation Feedback
Product Folder Links:
Description
voltage range
IN
Description
Table 6-27 for B0:B4 settings based on ISO protocol in application
Copyright © 2011–2017, Texas Instruments Incorporated
TRF7970A
www.ti.com
(1)